Let's roll up our sleeves and solve this. We have 509 and we're going to multiply it by 43, essentially adding 509 to itself 43 times.
Step 1: 0 + 509 = 509
Step 2: 509 + 509 = 1018
Step 3: 1018 + 509 = 1527
Step 4: 1527 + 509 = 2036
Step 5: 2036 + 509 = 2545
Step 6: 2545 + 509 = 3054
Step 7: 3054 + 509 = 3563
Step 8: 3563 + 509 = 4072
Step 9: 4072 + 509 = 4581
Step 10: 4581 + 509 = 5090
Step 11: 5090 + 509 = 5599
Step 12: 5599 + 509 = 6108
Step 13: 6108 + 509 = 6617
Step 14: 6617 + 509 = 7126
Step 15: 7126 + 509 = 7635
Step 16: 7635 + 509 = 8144
Step 17: 8144 + 509 = 8653
Step 18: 8653 + 509 = 9162
Step 19: 9162 + 509 = 9671
Step 20: 9671 + 509 = 10180
Step 21: 10180 + 509 = 10689
Step 22: 10689 + 509 = 11198
Step 23: 11198 + 509 = 11707
Step 24: 11707 + 509 = 12216
Step 25: 12216 + 509 = 12725
Step 26: 12725 + 509 = 13234
Step 27: 13234 + 509 = 13743
Step 28: 13743 + 509 = 14252
Step 29: 14252 + 509 = 14761
Step 30: 14761 + 509 = 15270
Step 31: 15270 + 509 = 15779
Step 32: 15779 + 509 = 16288
Step 33: 16288 + 509 = 16797
Step 34: 16797 + 509 = 17306
Step 35: 17306 + 509 = 17815
Step 36: 17815 + 509 = 18324
Step 37: 18324 + 509 = 18833
Step 38: 18833 + 509 = 19342
Step 39: 19342 + 509 = 19851
Step 40: 19851 + 509 = 20360
Step 41: 20360 + 509 = 20869
Step 42: 20869 + 509 = 21378
Step 43: 21378 + 509 = 21887

So, 509*43 = 21887